The present invention relates to a clamping fixture for detachably fastening a disk-shaped tool on a rotatably driven working spindle. Clamping fixtures of this type are suited for use in portable power tools in particular, such as angle grinders, portable circular saws, etc.
Publication DE 196 49 514 A1 makes known a clamping fixture with which a disk-shaped tool is accommodated between a locknut and a supporting flange. When the working spindle is rotated, the supporting flange moves axially in the direction of the tool, which increases the clamping force. The supporting flange is spring-loaded in the direction away from the tool, so that, when the working spindle is not driven, the supporting flange is moved immediately and automatically away from the tool, which, in turn, allows the clamping screw to be loosened easily.
The known clamping device has been proven in practice. The disadvantage of the known clamping device, however, is that the supporting flange is automatically displaced away from the tool when the working spindle stops, without intervention by the operator. The locknut is therefore always easy to loosen when the drive is switched off, which can result in the locknut being loosened accidentally even though the operator intends to continue using the portable power tool.